
*********************************************************************
*** Regress Kyphoplasty outpatient on lags to find best fit 
*** Lag only 
cd /disk/agedisk3/medicare.work/poterba-DUA52260/jetson-dua52260/kyphon/substitutes/robustness/forwardonly
use groupspanel.dta, clear 

levelsof group, local(levels)
keep group dt pmt_amt 
reshape wide pmt_amt, i(dt) j(group)
tsset dt
mata: distanceLag = J(1,3,0)

* 3 columns: group, lag period, distance

set matsize 11000

** Only want to keep kyphoplasty pre-period 
local treatment_period =  mofd(mdy(12, 12, 2005))
replace pmt_amt999 = . if dt >= `treatment_period'

** Find max lag so that there are 3 years of pre-period data 
summarize dt 
local maxlag = `treatment_period' - r(min) - 36
	** Treatment period - min  = length of end window 

gen diff = 0 

*** Loop, storing leads lags and fit
foreach g of local levels {
	disp `g'
	* Skip Kypho group
	if `g' == 999{
			continue
		}

	foreach t of numlist 0/`maxlag'{
		*disp `t'
		qui replace diff =  (pmt_amt999 - L`t'.pmt_amt`g')^2
		qui summarize diff 
		local dist = r(sum)/r(N)
		mata: distanceLag=  distanceLag \ `g', `t', `dist'
		}
}

mata: st_matrix("distanceLag", distanceLag)


svmat distanceLag
keep distanceLag*

rename distanceLag1 laggroup
rename distanceLag2 lagperiod
rename distanceLag3 lagdistance

drop if laggroup == 0
save distancelag.dta, replace
********************************************************************************
*** Find best fit per group

cd /disk/agedisk3/medicare.work/poterba-DUA52260/jetson-dua52260/kyphon/substitutes/robustness/forwardonly
use distancelag.dta, clear
* Create best fit per group
keep laggroup lagperiod lagdistance
drop if mi(laggroup)
bysort laggroup: egen minlagdistance = min(lagdistance)
keep if lagdistance == minlagdistance
drop minlagdistance

* Prep for merge 
rename laggroup group
rename lagdistance mindistance
replace lagperiod = -1*lagperiod
rename lagperiod period 
save groupleadlags.dta, replace
